1. Field of the Invention
The present invention relates to anisotropic conductive films, methods of mounting semiconductor chips, and semiconductor devices, and more particularly, the invention relates to an anisotropic conductive film which is suitable for mounting a semiconductor chip so that an active element-formed surface thereof faces the substrate side, a method of mounting a semiconductor chip, and a semiconductor device.
2. Description of Related Art
In a method of mounting a semiconductor chip so that a surface thereof provided with an active element faces downward, i.e., in so-called xe2x80x9cflip chip mountingxe2x80x9d, anisotropic conductive films are often used. The anisotropic conductive film exhibits adhesive ability and also acts as a conductive medium between the semiconductor chip and the substrate. The anisotropic conductive film is a thin film and is formed as a long tape. In general, the anisotropic conductive film is composed of a binder, which is composed of a solid epoxy resin and a liquid epoxy resin, and conductive particles composed of metal-clad resin particles. The conductive particles are blended so that the volumetric ratio thereof is uniform over the binder. Additionally, metal particles may be used as the conductive particles. Conductive particles having a diameter of approximately 2 to 10 xcexcm, and mostly approximately 5 xcexcm, are predominantly used.
Herein, an example of a method of mounting a chip using a conventional anisotropic conductive film is shown in FIG. 5. First, an anisotropic conductive film 3 is attached to a substrate 2 provided with wiring 21, and then a semiconductor chip 1 is placed on the anisotropic conductive film 3 in such a manner that electrode pads 11 and the wiring 21 are opposed to each other. Next, the semiconductor chip 1 is pressed while being heated by a hot pressing tool 71 from a surface opposite to the surface provided with the electrode pads 11.
Because of an increase in fluidity by heating, the anisotropic conductive film 3 fills the space around the electrode pads 11 and the wiring 21, and further flows out of the bond area between the semiconductor chip 1 and the substrate 2 to adhere to the sides of the semiconductor chip 1. Some conductive particles 61 are sandwiched between the electrode pads 11 and the wiring 21.
When the anisotropic conductive film 3 is cured after thermocompression, the semiconductor chip 1 and the substrate 2 are bonded together by the anisotropic conductive film 3. In particular, the anisotropic conductive film 3 adhered to the sides of the semiconductor chip 1 forms fillets 34 and strengthens mechanical connection between the semiconductor chip 1 and the substrate 2. The conductive particles 61 sandwiched between the electrode pads 11 and the wiring 21 act as conducting media between the semiconductor chip 1 and the substrate 2.
However, the conventional technique described above gives rise to the following problems.
In the case of a low-profile semiconductor chip 1, when the semiconductor chip 1 is heated and pressed by the hot pressing tool 71, the anisotropic conductive film 3 adheres not only to the sides of the semiconductor chip 1, but also to the hot pressing tool 71, as shown in FIG. 5, by an adhered portion 35. If a portion of the anisotropic conductive film 3 frequently adheres to the hot pressing tool 71, the hot pressing tool 71 must be frequently cleaned accordingly, resulting in an increase in controlling workload in the thermocompression process for the semiconductor chip. Additionally, the appearance of the semiconductor chip in such a state is unfavorable.
However, in order to avoid the problems described above, if the area of the anisotropic conductive film 3 to be provided on the substrate 2 is set smaller than the area of the semiconductor chip 1 provided with the electrode pads 11, or if the heating temperature of the hot pressing tool 71 is set lower than that in the conventional technique, the strength of mechanical connection between the semiconductor chip and the substrate may become sufficient.
In order to overcome the drawbacks in the conventional technique described above, it is an object of the present invention to provide an anisotropic conductive film in which satisfactory strength of mechanical connection between a substrate and a semiconductor chip can be obtained, and also, in which the process for connecting the semiconductor chip and the substrate can be easily controlled by preventing the anisotropic conductive film from adhering to a hot pressing tool. It is another object of the present invention to provide a circuit substrate provided with the anisotropic conductive film. It is another object of the present invention to provide an electronic apparatus provided with the circuit substrate.
It is another object of the present invention to provide a semiconductor device in which a semiconductor chip is mounted by means of an anisotropic conductive film, in which satisfactory strength of mechanical connection between a substrate and the semiconductor chip can be obtained, and which can be prevented from adhering to a hot pressing tool.
It is another object of the present invention to provide a method of mounting a semiconductor chip using the anisotropic conductive film. It is another object of the present invention to provide a semiconductor device which is fabricated by the method of mounting the semiconductor chip. It is another object of the present invention to provide an electronic apparatus provided with the semiconductor device.
In order to achieve the objects described above, an anisotropic conductive film according to an exemplary embodiment of the present invention for bonding a semiconductor chip and a substrate to each other and for acting as an electrically conductive medium between the semiconductor chip and the substrate includes a first member and a second member disposed adjacent to the first member. The first member is composed of a material having characteristics with lower fluidity than that of the second member.
In the anisotropic conductive film according to the exemplary embodiment constructed as described above, when the semiconductor chip is connected to the substrate by thermocompression bonding of the semiconductor chip to the anisotropic conductive film attached to the substrate with a hot pressing tool, the first member inhibits the second member from flowing toward the sides of the semiconductor chip. Thereby, it is possible to prevent the second member from adhering excessively to the sides of the semiconductor chip in such a manner that the adhesion reaches the hot pressing tool. Consequently, the process for connecting the semiconductor chip and the substrate can be easily controlled.
An anisotropic conductive film according to another exemplary embodiment of the present invention for bonding a semiconductor chip and a substrate to each other and for acting as an electrically conductive medium between the semiconductor chip and the substrate includes a first member and a second member disposed adjacent to the first member. The first member is composed of a material which exhibits characteristics with lower fluidity than that of the second member when the semiconductor chip and the substrate are bonded together.
In the anisotropic conductive film according to the exemplary embodiment constructed as described above, since the first member has lower fluidity than that of the second member at the point where the semiconductor chip is connected to the substrate by thermocompression bonding of the semiconductor chip to the anisotropic conductive film attached to the substrate with a hot pressing tool, the first member can inhibit the second member from flowing toward the sides of the semiconductor chip. Thereby, it is possible to prevent a material used for the second member from excessively adhering to the sides of the semiconductor chip in such a manner that the adhesion reaches the hot pressing tool. Consequently, the process for connecting the semiconductor chip and the substrate can be easily controlled.
In an anisotropic conductive film according to another exemplary embodiment of the present invention, the second member has substantially the same shape as that of a surface provided with electrodes of the semiconductor chip.
In the anisotropic conductive film according to the exemplary embodiment constructed as described above, when the semiconductor chip is connected to the substrate, the amount of the second member flowing toward each side of the semiconductor chip can be substantially equalized, and a fillet with an excessive size is not formed on a specific side.
In an anisotropic conductive film according to another exemplary embodiment of the present invention, the second member has substantially the same area as that of a surface provided with electrodes of the semiconductor chip.
In the anisotropic conductive film according to the exemplary embodiment constructed as described above, when the semiconductor chip is connected to the substrate, the amount of the second member flowing toward each side of the semiconductor chip can be suppressed to such an extent that a fillet having an appropriate size can be formed at each side.
A circuit substrate according to another exemplary embodiment of the present invention includes any one of the anisotropic conductive films described above.
In the circuit substrate according the exemplary embodiment constructed as described above, when the semiconductor chip is subjected to thermocompression bonding, the anisotropic conductive film is prevented from excessively flowing to the periphery of the semiconductor chip and adhering to the other region on the circuit substrate. The semiconductor chip can also be securely connected, and thus a highly reliable circuit substrate can be provided.
In addition, an electronic apparatus according to another exemplary embodiment of the present invention includes the circuit substrate.
In the electronic apparatus according to the exemplary embodiment constructed as described above, since the circuit substrate having high reliability in mounting a semiconductor chip is used, the reliability of the electronic apparatus itself is increased.
A semiconductor device according to another exemplary embodiment of the present invention includes a substrate on which a semiconductor chip is mounted by an anisotropic conductive film. The anisotropic conductive film includes a first member corresponding to a peripheral zone and a second member located in the, more central region in comparison with the first member. The first member is composed of a material having characteristics with lower fluidity than that of the second member.
In the semiconductor device according to the exemplary embodiment constructed as described above, when the semiconductor chip is bonded to the substrate by thermocompression, the first member inhibits the second member from flowing toward the sides of the semiconductor chip. Thereby, the second member does not excessively adhere to the sides of the semiconductor chip, and a semiconductor device having a good appearance can be provided.
In a semiconductor device according to another exemplary embodiment of the present invention, the second member has substantially the same shape as that of a surface provided with electrodes of the semiconductor chip.
In the semiconductor device according to the exemplary embodiment constructed as described above, the amount of the second member flowing toward each side of the semiconductor chip can be substantially equalized, and a fillet with an excessive size is not formed on a specific side.
In a semiconductor device according to another exemplary embodiment of the present invention, the second member has substantially the same area as that of a surface provided with the electrodes of the semiconductor chip.
In the semiconductor device according to another exemplary embodiment constructed as described above, when the semiconductor chip and the substrate are connected to each other, the amount of the second member flowing toward each side of the semiconductor chip can be suppressed to such an extent that a fillet having an appropriate size can be formed at each side.
A method of mounting a semiconductor chip according to another exemplary embodiment of the present invention so that one surface provided with electrodes of the semiconductor chip is opposed to a surface provided with electrodes of a substrate includes the steps of attaching an anisotropic conductive film including a first member and a second member disposed adjacent to the first member to the surface provided with the electrodes of the substrate, placing the semiconductor chip on the anisotropic conductive film, and connecting the semiconductor chip to the substrate by pressing the semiconductor chip while heating by a hot pressing member.
In the method of mounting the semiconductor chip according to the exemplary embodiment as described above, when, the semiconductor chip is connected to the substrate by thermocompression bonding of the semiconductor chip to the anisotropic conductive film attached to the substrate with a hot pressing tool, the first member inhibits the second member, having higher fluidity than that of the first member, from flowing toward the sides of the semiconductor chip. Thereby, it is possible to prevent the second member from excessively adhering to the sides of the semiconductor chip in such a manner that the adhesion reaches the hot pressing tool. Consequently, the process for connecting the semiconductor chip and the substrate can be easily controlled.
In a method of mounting a semiconductor chip according to another exemplary embodiment of the present invention, the first member has characteristics with lower fluidity than that of the second member.
In the method of mounting the semiconductor chip according to the exemplary embodiment as described above, the first member can securely inhibit the second member from flowing toward the sides of the semiconductor chip, and the adhesion of the second member to the hot pressing tool can be prevented.
In a method of mounting a semiconductor chip according to another exemplary embodiment of the present invention, the second member has substantially the same shape as that of the one surface described above.
In the method of mounting the semiconductor chip according to the above exemplary embodiment, the amount of the second member flowing toward each side of the semiconductor chip can be substantially equalized, and a fillet with an excessive size is not formed at a specific side.
In a method of mounting a semiconductor chip according to another exemplary embodiment of the present invention, the second member has substantially the same area as that of the one surface described above.
In the method of mounting the semiconductor chip according to the above exemplary embodiment, when the semiconductor chip and the substrate are connected to each other, the amount of the second member flowing toward each side of the semiconductor chip can be suppressed to such an extent that a fillet having an appropriate size can be formed at each side.
A method of mounting a semiconductor chip according to another exemplary embodiment of the present invention for mounting the semiconductor chip so that one surface provided with electrodes of the semiconductor chip is opposed to a surface provided with electrodes of a substrate includes the steps of heating a region located more centrally from a peripheral zone of an anisotropic conductive film comprised of a thermoplastic resin to increase the fluidity of the anisotropic conductive film, attaching the anisotropic conductive film to the surface provided with the electrodes of the substrate, placing the semiconductor chip on the anisotropic conductive film, and connecting the semiconductor chip to the substrate by pressing the semiconductor chip while heating by a hot pressing member.
In the method of mounting the semiconductor chip according to the above exemplary embodiment, since the fluidity of the heated region is increased, in the step of connecting the semiconductor chip to the substrate, the heated region flows toward the sides of the semiconductor chip, and also the unheated region suppresses the excessive flow thereof. Thereby, it is possible to prevent the anisotropic conductive film from excessively adhering to the sides of the semiconductor chip and reaching a hot pressing tool. Consequently, the process for connecting the semiconductor chip and the substrate can be easily controlled.
In a method of mounting a semiconductor chip according to another exemplary embodiment of the present invention, the anisotropic conductive film is formed so that the region has substantially the same shape as that of the one surface described above.
In the method of mounting the semiconductor chip according to the above exemplary embodiment constructed as described above, the amount of the second member flowing toward each side of the semiconductor chip can be substantially equalized, and a fillet with an excessive size is not formed on a specific side.
A method of mounting a semiconductor chip according to another exemplary embodiment of the present invention for mounting the semiconductor chip so that one surface provided with electrodes of the semiconductor chip is opposed to a surface provided with electrodes of a substrate includes the steps of attaching a frame-shaped anisotropic conductive film to the surface provided with the electrodes of the substrate, providing an anisotropic conductive adhesive having higher fluidity than that of the anisotropic conductive film in the region inside the anisotropic conductive film, placing the semiconductor chip on the anisotropic conductive adhesive, and connecting the semiconductor chip to the substrate by pressing the semiconductor chip while heating by a hot pressing member.
In the method of mounting the semiconductor chip according to the exemplary embodiment constructed as described above, when the semiconductor chip and the substrate are connected to each other by thermocompression bonding of the semiconductor chip to the anisotropic conductive film attached to the substrate by a hot pressing tool, the frame-shaped anisotropic conductive film inhibits the anisotropic conductive adhesive in the interior region from flowing toward the sides of the semiconductor chip. Thereby, it is possible to prevent the anisotropic conductive adhesive from excessively adhering to the sides of the semiconductor chip and reaching the hot pressing tool. Consequently, the process for connecting the semiconductor chip and the substrate can be easily controlled.
In a method of mounting a semiconductor chip according to another exemplary embodiment of the present invention, the region inside the anisotropic conductive film has substantially the same shape as that of one surface described above.
In the method of mounting the semiconductor chip according to the above exemplary embodiment, when the semiconductor chip and the substrate are connected to each other, even if the anisotropic conductive adhesive flows toward the sides of the semiconductor chip, since the flowing amount is too small to form fillets having an excessive size, the anisotropic conductive film does not adhere to, the hot pressing tool.
A semiconductor device according to another exemplary embodiment of the present invention is fabricated by the method of mounting a semiconductor chip according to any one of the above exemplary embodiments.
In the semiconductor device according to the above exemplary embodiment constructed as described above, the reliability in connecting the semiconductor chip can be increased, and the size of the fillets formed at the sidles of the semiconductor chip can be set in response to the height of the semiconductor chip to be mounted. Consequently, it is possible to provide a semiconductor device having high reliability in connecting the semiconductor chip and the substrate and also having good appearance.
Furthermore, an electronic apparatus according to another exemplary embodiment of the present invention includes the semiconductor device according to the above exemplary embodiment.
In the electronic apparatus according to the exemplary embodiment constructed as described above, since the semiconductor device in which fillets having an appropriate size are formed and which has satisfactory mechanical connection is included, the functional reliability of the electronic apparatus is enhanced.
With respect to the material for the substrate in each means described above, a substrate composed of an organic material, such as a plastic substrate or a flexible substrate, or a substrate composed of an inorganic material, such as a ceramic substrate, may be used.